Preparation of 21-halo steroids



United States PatentO PREPARATION OF ZI-HALO STEROIDS Percy L. Julian, Chicago, and William J. Karpel, Oak

Park, Ill., assignors to The Glidden Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application May 13, 1953, Serial No. 354,868

7 Claims. (Cl. 260-39747) Application Serial. No. 143,146 is directed to the-treatment of 16-bromo-17a-hydroxy-20-keto-2l-halo steroids of the C21 series with a salt of an alkali metal hydroxide and a' lower carboxylic acid whereby the 21-halo group is replaced by the acyloxy group of the salt. Application Serial No. 184,124 is directed, inter alia, to the treatment of saturated 11,20-diketo-17a-hydroxy-21-halo pregnanes with a salt of an alkali metal hydroxide and a lower carboxylic acid whereby the 21-halo group is replaced by the acyloxy group of the salt. prior applications point out the desirability of producing such 21-acyloxy compounds.

It is the purpose of the present invention to prepare 17a-hydroxy-20-keto-2l-halo steroids of the C21 series, the preparation of which are both broadly described, and in many cases specifically described, in the afore-mentioned applications.

It has been found that when saturated 17a-hydroxy- Both of these.

17,3-acetyl steroids are treated with bromine, one of the hydroxy compounds. These can be either directly treat-.

ed with bromine, preferably after saturation of unsaturated compounds, or the l6-bromo group can first be removed, as by treament with Raney nickel, and the resulting 17- hydroxy compound then brominated at C21. Alternatively, the 16,17-oxido group can be reduced by lithium aluminum hydride with intermediate protection of the 20- keto group by formation of a cyclic ethylene ketal.

The following examples are illustrative:

EXAMPLE 1 Preparation of 5,6,16,21-tetrabr0m0-pregnane-3}3,I7a.- di0l-20-0ne-3 monoacetate A solution of one gram of 16,17a-oxidopregnenolone acetate in 10 ml. of acetic acid was treated with a solution of 0.430 g. of bromine in 4.30 ml. of acetic acid at room temperature. After the bromine color had all disappeared, 1.5 ml. of 30% HBr in acetic acidand 10 ml. of carbon tetrachloride was added and the mixture was allowed to stand at room temperature for one-half hour. An additional 0.430 g. of bromine in 4.30 :ml.

2,789,989 Patented Apr. 23, 1957 "ice of acetic acid was then added. After standing for 1 /2 hours at room temperature, the bromine color had disappeared. The carbon tetrachloride was removed in vacuo and the remaining acetic acid solution was poured into water. The crystalline precipitate was filtered, washed well with water and air dried. 1.79 g., M. P. 145 -147 dec.

, EXAMPLE 2 Preparation of 16-br0m0-21-i0d0-5-pregnene-3,8,17a-di0l- 20-0ne-3 monoacetate The tetrabromide from Example 1 was dissolved in 25 ml. of benzene and a solution of 4.0 g. of sodium iodide in 25 ml. of ethanol was added. This mixture was allowed to stand at room temperature for 20 hours, and then poured into a large volume of ether and water. The ether layer was washed with dilute sodium thiosulfate and water, dried and concentrated in vacuo to a tan solid residue.

'EXAMPLE 3 The bromination of 16,17-0xia'0-5-pregnene-3B-0l-20- one in acetic ,acid

A solution of one gram of 16,17a-oxido-pregnenolone in 10 ml. of acetic acid was treated with 0.485 g. of

bromine'in 4.85 mLof acetic acid at room temperature.

After the bromine color had all disappeared, 1.5 ml. of

30% HBr in acetic acid and 15 ml. of carbon tetrachloride were added. A precipitate appears which goes back into solution on standing. After one-half hour at room temperature an additional 0.485 g. of bromine in 4.85 cc. of acetic acid was added. After standing for one hour at room temperature an additional 0.485 g. of bromine in 4.85 cc. of acetic acid was added. After standingfor one hour at room temperature, the bromine color had disappeared. The carbon tetrachloride was removed in vacuo and the acetic acid solution was poured into water. The crystalline precipitate was filtered, washed well with water and air dried. 2.14 g., M. P. 145147 dec. There was no depression in melting point on admixture with the product from Example 1; therefore, acetylation at position 3 has taken place in acetic acid in the presence of HBr.

EXAMPLE 4 Treatment of 16,17-0xid0-pregnane-3-ol-20-one acetate To a solution of 1 gram of 16,17-oxido-pregnane-3-ol- 20-one acetate in 10 ml. of acetic acid is added 1.5 ml. of 30% HBr in acetic acid and 15 ml. of carbon tetrachloride. Af'ter one-half hour at room temperature there is added 0.430 g. of bromine in 4.30 ml. of acetic acid. The mixture is allowed to stand at room temperature until the bromine color disappears. The carbon tetrachloride is then removed in vacuo and the acetic acid solution poured into water, the precipitate filtered,

washed well with water and dried.

EXAMPLE 5 16,1 7-oxido-5 pregame-313,21 -di0l-20-one 21-m0n0acetate acetic acid. After the solution had stood for ten minutes at room temperature, a second molar equivalent of bromine, 4.3 g. in 30 ml. of carbon tetrachloride, was added portionwise at room temperature with stirring during a forty-minute period. The reaction mixture was allowed to stand for an additional fifteenminutes and then'evapoan nna ratedin vacuo with a minimum of heating toremove the carbon tetrachloride. The remaining suspension was poured into Water, filtered and the separated solid washed with water and dried at 40. The solid,- 17.9',g.-,:Was dissolved in 75 ml. of benzene and 175 ml. of methanol, and after the addition of 5.2 g. of hydrogen bromide in 15 ml. of methanol, the solution was allowed to stand at room temperature for ten hours. The ethereal extract of the reaction mixture which had been diluted with water was washed with water, dried, concentrated to 20 ml. and diluted with 155 ml. of benzene. After the addition of a solution of 366.5 g; of sodium iodide in 175 rrtii of absolute ethanol, the mixturewas allowed to stand at. room temperature for twenty-two hours. It was them. diluted well with water and extracted with ether; The ether extract was washed with 3% sodium thiosulfate solution and then with Water. The cream-colored'res'idue (14.5 g.) remaining after removalof ether invacuo was dissolved in 300 ml. of acetone containing 42ml. of acetone containing 42 g. of freshly-fused potassium acetate. The mixture was refluxed for four and one-half hours, then concentrated to a small volume, diluted with water and extracted with ether. The water-washed and dried ethereal solution gave upon concentration toa small volume, 5.5 g. of-16,17-oxido-5-pregnene-3 3,2l-diol-20- one 21-monoacetate melting at 180-188. A reslurry of the monoacetate in ether yielded 5.0 g. of material melting at 188190. Further recrystallization from acetone gave needles melting at 190-192". (005 +149 (8.7 mg. made up to 2 ml. with chloroform, a +0.065, l, 1 dm.).

Analysis.-Cal-c. for CsHszOs: C=71'.11; H=8.30. Found: (1:70.86; H=8.33.

EXAMPLE 6 Preparation of 21-br0m0-pregnane-3,17ot-di0l-1I,20-di0rie and i ts 3 monoacetat'e To a 4 g. solution of -oxiodopregnan-3a-ol11,20-

dione acetate in 40 cc. of acetic acid and 40 cc. of CHCla cooled to there was added 4 cc. of 32% HBr in acetic acid. After allowing to stand for ten minutes, a solution of 1.76 g. of bromine in 18 cc. of acetic acid was added rapidly and the mixture then held at room temperature for 20 minutes until the bromine hadbecn absorbed. The reaction mixture was concentrated in vacuo to a crystalline slush, then slurried with alcohol free ether, chilled and filtered. There was obtained 3.38 g., M."P; 224- 230 dec. of the 21-bromo-bromhydrin.

This was treated at room temperature with a mixture of 27 cc. of benzene and 72cc. of methanolcontaining 1.9 g. of anhydrous HBr for 12 hours. The reaction mixture was diluted with water and extracted with ether and washed with Water to neutrality. The. solution was dried and concentrated in vacuo to. a crystalline. residue.

' EXAMPLE 7 Preparation of pregame-3a,]7a-diol-1I,20-di0ne- 3- monoacetate A solution of 60 g. of 16,17-oxido-pregnan-3u-ol11,20- dione acetate in 300 cc. of glacial acetic acid was cooled to 15 and treated with a solution of 60 cc. of 32% bydrobromic acid in acetic acid. The reaction mixture was held at 20 for 15 minutes, whereupon the crystalline bromhydrin which separated was filtered and washedwith ether. After drying the bromhydrin in vacuo with minimum heating during several minutes, it was stirred and 4 EXAMPLE 2 Preparation of 21-br0m0-pregnane-3aJ7a-di0l-3,20-dione and its S-acetate A solution of 72 g. of pregnane-Za,17ot-diol-11,20-dione 3-monoacetate in 720 cc. of acetic acid at 30 was treated with 7.2 cc. of 32% HBr in acetic acid and a solution of 31 g. of bromine in 320 cc. of acetic acid during a 5- .minute period. After cooling and filtering, there was obtained 62.5 g. of the 21-bromo derivative, M. P. 235". Recrystallization raised the melting point to 245.

Analysis.--Calc. forCzaHazOsBr: C=58.97; H=6.89. Found: C=58.85; H=7.17.

The filtrate was dehalogenated with zinc dust, diluted with water and extracted with ether. The ethereal solution, upon concentration, yielding a recovery of 15.5 g. of starting material, M. P. 201-202. The 62.5 g. of 21- bromo derivative was hydrolyzed by stirring with a mixture of 500 cc. of benzene and 1500 cc. of methanol containing 39 g. of anhydrous HBr for 8 hours. The hy- -drolysis mixture was diluted with ether and Washed with water to neutrality and then concentrated in vacuo to a totally crystalline residue.

EXAMPLE 9 Preparation of 21 -br0m0-pregnane-3a,1 7u-di0l-1 1,20 clione A solution of 5.0 g. of pregnane-3 a,17a-diol-11,20-dione 3-monoacetate in 200 cc. of methanol was refluxed for 1 /2 hours with a solution of 5 g. of potassium bicarbonate in 15 cc. of water. 75 cc. of water was added and concentrated in vacuo to a crystalline slush and cooled. Filtration attorded 4.2 g. of the free diol, M. P. 201". A solution 1.74 g. of the 306,170t-dl0l in 17 cc. of chloroform was treated at room temperature with a few drops of dry HBr in chloroform and followed dropwise with a solution of 0.84 g. of bromine in 5 cc. of chloroform during 10 minutes. The solution was concentrated in vacuo to residue. The dried 21-bromo derivative was dissolved in 35 cc. of dry acetone and refluxed for 4 /2 hours with 5 g. of anhydrous potassium acetate. Concentrated and diluted with water and filtered. The dried crude product, upon crystallization from ethyl acetate, afforded 1.0 g. of pregnane-3u,17a,21-triol 11,20 dione 21 monoacetate, M. P. 216.

EXAMPLE l0 Preparation of 21-br'0m0pregnane-3a,1 7u-di0ll2,20'

dione 3 acetate To a solution of 3.9 g. of pregnane-3a,17a-diol-12,20- f diorie 3-acetate (M. P. 167 to 169 C.) in 40 cc. of glacial acetic acid, 2 drops of a 30% solution of hydrogen bromide 'in glacial acetic acid were added. Thereafter, at about 25 C., 1.8 g. of bromine in 4 cc. of glacial acetic acid were added dropwise during about 45 minutes, and the resulting mixture, after being stirred for about 15 minutes, was diluted with cc. of cold water. The resulting emulsion was extracted with a mixture of ether and methylene chloride, and the extract was washed with water, aqueous sodium bicarbonate and finally with Water to neutrality. The Washed extract was dried over anhydrous sodium sulfate and then concentrated to obtain 2.6 g. of a product melting at 169 to 177 C. From the mother liquor an additional 0.24 g. of material meltingat 156 to 166 C. was obtained. A portion of this material was treated with sodium iodide and sodium bisulfite in acetone solution as described in copending application of Julian and Karpel, Serial No. 116,415, filed September 17, 1949. In this manner a dehalogenated product melting at 147-155 C., which did not depress the -melting point of pregnane-h,17c-diol-12,20-dionc 3-acetate, was obtained. This indicates that the bromine atom was substituted in the 21-position and hence the brominated product was ZLbLOmOPIEgHaHC-Sa,l7bc=di0l- -12,20-dione -3=-acetate.

It will be appreciated that the foregoing examples are illustrative and that many variations can be employed without departing from the spirit of the invention. Thus, other esters than the 3-acetoxy ester can be employed, such as the benzoate, propionate, butyrate, hemisuccinate, etc. Either a free 3-OH or a 3-acetoxy group is to be preferred, however, when it is ultimately desired to have a 3-keto group, and this 3-keto group is to be formed after the introduction of the 21-bromo group.

Since a keto group is conveniently formed by oxidation of a secondary OH group, an easily hydrolyzable acyloxy group is desirable in such case. 3-keto compounds can also be treated in accordance with the present invention.

It is seen that the particular substituents on the 10,133- dimethyl-cyolopentanopolyhydrophenanthrene are not important to the present invention other than the l7m-hydI'OXY-17oz-3C61IY1 groups. Thus, oxygenated substituents on Ring C can be present either as carbonyl, acyloxy, hydroxy, enol esters, etc. on either the 11- or lZ-carbon atoms.

Also where unsaturated compounds, such as A-S compounds, are used, the double bond can be saturated by other means than bromine. Thus, 5,6-dichloro compounds can be used. Thus, bromination of a,6,8-dichloro-l6-bromo-allopregnane-3,17a-di0l-20-one 3-acetate yields 5a,6fidichloro-l6,2l-dibromo-allopregnane- 3,17a-diol-20-one 3-acetate, M. P. 189-193 C.

Attention is directed to our copending application Serial No. 354,424, filed May 11, 1953, wherein the conversion of the 21-bromides herein described to 21-acy loxy compounds is more fully described and claimed.

Having described the invention, what is claimed is:

1. The process which comprises treating a compound of the general formula CH: B=0

in which x and x are selected from the group consisting of hydrogen, bromine and chlorine substituents, and y is selected from the class consisting of hydrogen and bromine substituents, and z is selected from the class consisting of the hydroxy group and an OR group in which R is an acyl radical of a lower hydrocarbon carboxylic acid, with bromine whereby there is formed the corresponding 21-bromo derivative.

2. The process of claim 1 in which x x and y are bromine and z is an acyloxy group of a lower hydrocarbon carboxylic acid.

3. The process of claim 2 in which the acyloxy group is the acetoxy group.

4. The process of claim 1 in which x and x are chlorine, y is bromine and z is an acetoxy group.

5. The process of claim 1 in which x and x are hydrogen, y is bromine and z is an acetoxy group.

6. The process which comprises treating a saturated 3 acyloxy-10,13-dimethyl-l7a-hydroxy-17,3-acetyl-cyclopentanopolyhydrophenanthrene steroid in which the acyloxy group is an acyloxy group of a lower hydrocarbon carboxylic acid, with bromine, whereby a 2l-bromo-17w hydroxy steroid is formed.

7. The process which comprises treating a saturated 10,13 dimethyl 3,170: dihydroxy 17/3 acetyl cyclopentanopolyhydrophenanthrene steroid with bromine, whereby a 2l-bromo-17a-hydroxy steroid is formed.

References Cited in the file of this patent UNITED STATES PATENTS 2,359,773 Marker Oct. 10, 1944 2,409,043 Inhoffen Oct. 8, 1946 2,541,104 Sarctt Feb. 13, 1951 2,596,562 Kaufmann May 13, 1952 2,596,563 Kaufmann May 13, 1952 OTHER REFERENCES Gallagher: Iour. Am. Chem. Soc., 71, 3262-3263 (1949). 

1. THE PROCESS WHICH COMPRISES TREATING A COMPOUND OF THE GENERAL FORMULA 